Electron discharge device anode fin having heat distortion preventive means incorporated therein

ABSTRACT

Heat distortion preventive means in the form of expansion openings are provided in the leading edge of anode fins for increased stability during operation and longer life expectancy.

United States Patent Cyril Droppa;

Charles C. I-Iendrickson, Emporium, Pa. [21 Appl. No. 786,185

[22] Filed Dec. 23, 1968 [45] Patented Mar. 2, 1971 [73] AssigneeSylvania Electric Products Inc.

[72] Inventors [54] ELECTRON DISCHARGE DEVICE ANODE FIN HAVING HEATDISTORTION PREVENTIVE MEANS INCORPORATED THEREIN 6 Claims, 5 DrawingFigs.

[52] US. Cl 313/39, 313/40, 313/46, 313/299, 313/351 [51] Int. Cl H0ljl/36, A HOlj 19/36 [50] Field ofSearch 313/1 1, 39, 40, 45, 46, 299,309, 351, 356, 33, 38, 326; 165/81, 185

[56] References Cited UNITED STATES PATENTS 2,837,672 6/1958 Small eta1. 313/299X 3,428,844 2/1969 Droppa 313/45X FOREIGN PATENTS 446,7675/1936 Great Britain 165/81 Primary Examiner-John Kominski AssistantExaminer-E. R. La Roche Attorneys-Cyril A. Krenzer, Norman J. O Malleyand William H. McNeil] ABSTRACT: Heat distortion preventive means in theform of expansion openings are provided in the leading edge of anodefins for increased stability during operation and longer lifeexpectancy.

SHEET 1 OF 2 PATENTEU MAR 2197i -I3 jf ll- INVENTORS CYRIL DROPPA & BYCHARLES C. HENDR'CKSON ATTORNEY PATENTEDNAR 2m: 8.567.982

SHEET 2 [IF 2 INVENTORS CYRIL DROPPA & YCHARLES C. HENDRICKSON ATTO RNEY ELECTRON DISCHARGE DEVICE ANODE FIN HAVING HEAT DISTORTIONPREVENTIVE MEANS INCORPORATED THEREIN BACKGROUND OF THE INVENTION Thisinvention relates to electron discharge devices and more particularly tointernalanode fins utilized therein. Anode fins may be of single orplural, parallel construction and are employed to achieve desirableanode current characteristics in, for example, horizontal deflectionamplifier tubes used in color television receivers. While this type ofanode design provides this desirable control of anode current, theleading edges of the fins, which extend close to the cathode, aresubject to very high current densities and consequently very hightemperatures. The high temperatures cause the fin material to expandalong the leading edge thereof. The repeated expansion and contractionthat occurs during the operating life of the tube, for example, in atelevision receiver, causes the material to stretch, and the leadingedge of the fin to become permanently deformed. This deformation mayappear as a side-to-side rippled effect along the edge or may evenproduce a twisting action which exposes the side of the fin to thecathode of the tube.

When this occurs the tube characteristics are adversely affected. Forexample, the anode or plate current decreases, and the screen gridcurrent increases, thus decreasing the plate to screen current ratio.The inefiicient operation that results therefrom further raises tubetemperatures and makes the tube susceptible to control grid and screengrid emission and their associated problems. This chain of events has adetrimental effect on overall tube performance, reliability, and lifeexpectancy. In a television receiver, these effects are manifested in adecrease in the width of the scan and a reduction in the high voltage tothe picture tube. If the fin distortion becomes severe enough, it maycause the fin to short out to either the beam plate or the screen grid,thus rendering the tube inoperative.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of theinvention to obviate the disadvantages of the prior art devices.

It is a further object of the invention to enhance the operatingcharacteristics of tubes employing anode fins.

It is yet another object of the invention to provide a more durableanode fin.

Other objects of the invention are to increase the life expectancy andstability of operating characteristics of tubes employing anode fins.

These objects are accomplished in one aspect of the invention by theprovision of an anode fin having heat distortion preventive meansincorporated therein.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENTS For a better understanding of the present invention,together with other and further objects, advantages and capabilitiesthereof, reference is made to the following disclosure and appendedclaims in connection with the above-described drawings.

Referring now to the invention with greater particularity, in FIG. 1there is shown an electron discharge device 10 of a type known as a beampower tube and used, for example, as a horizontal deflection amplifierin television receivers. The device 10 is comprised of a glass envelope12 and an electrode cage 14 which is positioned between a pair ofsupporting micas 16, only one of which is shown.

The electrode cage comprises a cathode 18 having an electron emissivematerial 20 thereon, a control grid 22, a screen grid 24, abeam-confining plate 26, and an anode 28 having anode fin 30 projectinginwardly of the cage toward the cathode. If desired, heat-radiatingwings 32 may be attached to the fin 30 or to some other suitablelocation on the anode 28.

The anode or plate 28 is comprised of halves 34 and 36 having,respectively, end walls 38 and 40. Oppositely disposed sidewalls 42 and44 project from end wall 38 and are formed to provide outwardlyextending longitudinal joining flanges 46 and 48 at the portion thereofremote from end wall 38.

Likewise, oppositely disposed sidewalls 50 and 52 project from end wall40 and are formed to provide outwardly extending longitudinal joiningflanges 54 and 56 at the portion thereof remote from end wall 40. Anodefins 30 are fixedly positioned between pairs of the joining flanges sothat their leading edges 58 project inwardly toward the cathode. Thefins 30 may be comprised of a substantially U-shaped, double thicknessof material, as shown in FIG. 1, as two spaced-apart, parallel membersof single thickness, as shown in FIG. 2, or as a single thickness ofmaterial. The invention disclosed herein is equally adaptable to any ofthe above-described fin designs.

The anode 28 and fins 30 for this type of tube are generally fabricatedfrom high expansion alloys; i.e., alloys having a coefficient ofexpansion in the neighborhood of 20 X 10"/ C/in. Thus, a plate fin 1.75inches long would experience an expansion of .021 inches at 600 C. This,however, is true for a fin that is at a uniform temperature and that isfree to expand in all directions without hindrance. In an operatingtube, however, the plate fin has a very pronounced temperature gradientalong the leading edge and also from the edge back to the main portionof the plate. Furthermore, the back of the fin is staked tightly to themain plate structure and is not free to expand. It is these conditionsthat produce such severe'deformation and buckling of the fins.

Another condition affecting the plate response to temperature change isthe material from which the plate and fin are fabricated. Generally,this material is bimetallic; for example, copper-cored nickel oraluminum-coated steel. The unequal temperature distribution over thesurface of the fin together with the bimetallic effect of the dissimilarlayers produces severe stresses in the fin. These stresses and thebimetallic effect cause the fin to bend in a sideways direction. Afterrepeated heating and cooling with the consequent application of stress,the material crystallizes and becomes permanently deformed and will notreturn to its original shape.

This condition is alleviated by this invention by providing the fins 30with heat distortion preventive means 60, as may be seen in FIGS. 3, 4and 5. The heat distortion preventive means 60, in the instant concept,take the form of expansion openings 62. In FIG. 3 these openings 62 areconfigured as substantially V-shaped notches 64. They are three innumber, substantially equally spaced-apart in the embodiment shown, butthis number may vary depending upon the length of the fin.

ln FIG. 4 the openings are provided in the form of rectangular slots 66,spaced as in the embodiment described above.

In FIG. 5 is shown the locking tabs 68 which lock the rear portion ofthe fins 30 to the flanges on the anode halves.

The expansion openings 62 in the leading edges of the fins 30 allowcontrolled expansion thereof during operation without undesirablestresses being applied and the consequent buckling thereof which was sodetrimental to prior art devices.

For even further strengthening, either the fins 30 and the main portionof the anode 28 or both may be provided with laterally extendingreinforcing beads 70. When both the fins and anode are provided with thebeads 70, they should be aligned, as is shown in FIG. 5. Also, the beadson the fins should be equally spaced between the expansion openings.

Thus, it will be seen that there is herein provided a new and novelelectron discharge device having obvious advantages over the prior art.The heat distortion preventive means greatly enhance the operatingcharacteristics of the device. The anode fin is far more durable thanprior art tins and the device itself has an increased life expectancywith greater stability of operating characteristics over the lifethereof.

While there have been shown and described what are at present consideredthe preferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention as defined bythe appended claims.

We claim:

1. in an electron discharge device having a cathode and at least onegrid; an anode surrounding said cathode and said grid; and a fin formedto project inwardly of said anode to a point closer to said cathode thanany part of said anode, the improvement comprising: heat distortionpreventive means incorporated in said fin.

2. The device of claim 1 wherein said heat distortion preventive meanscomprises a plurality of expansion openings formed in the edge of saidfin facing said cathode.

3. The device of claim 2 wherein said openings are configured assubstantially V-shaped cutout areas.

4. The device of claim 2 wherein said expansion openings aresubstantially rectangular slots.

5. The device of claim 4 wherein said slots are three in number and aresubstantially equidistantly spaced along said edge of said fin.

6. The device of claim 2 wherein said expansion openings extend lessthan the width of said fin.

1. In an electron discharge device having a cathode and at least onegrid; an anode surrounding said cathode and said grid; and a fin formedto project inwardly of said anode to a point closer to said cathode thanany part of said anode, the improvement comprising: heat distortionpreventive means incorporated in said fin.
 2. The device of claim 1wherein said heat distortion preventive means comprises a plurality ofexpansion openings formed in the edge of said fin facing said cathode.3. The device of claim 2 wherein said openings are configured assubstantially V-shaped cutout areas.
 4. The device of claim 2 whereinsaid expansion openings are substantially rectangular slots.
 5. Thedevice of claim 4 wherein said slots are three in number and aresubstantially equidistantly spaced along said edge of said fin.
 6. Thedevice of claim 2 wherein said expansion openings extend less than thewidth of said fin.